Is a child who was conceived shortly before her mother converted considered Jewish? The mother discovered she was pregnant and this information was provided to the mikveh witnesses on the day of the immersion/conversion. Please explain what, if anything the child has to do in the future to be considered halachically Jewish

ב"ה Shalom In principle, even a child conceived before the mother converted, is considered Jewish. (See Talmud Yevamot 97b).However, there are still issues involved regarding the family relationship to a brother who was later conceived and born Jewish. Nonetheless, if the converting mother was pregnant at the time of her immersion in the Mikveh, the child does not need additional immersion in the mikveh and becomes Jewish with the mother. However, the existence of the pregnancy must be brought to the attention of the Bet din. שו"ע יור"ד רסח: ו, דגול מרבבה ופתחי תשובה שם)). If not, there are ramifications to be dealt with. (See at length שו"ת יחל ישראל ח"א סי' פט) Since, some of the issues are complex ,it should be dealt with by the local Jewish Bet Din which was involved in the conversion. All the best.